From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79B74C433DF for ; Thu, 20 Aug 2020 22:51:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 511FA207DF for ; Thu, 20 Aug 2020 22:51:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="uUq1JRoV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728582AbgHTWvN (ORCPT ); Thu, 20 Aug 2020 18:51:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728368AbgHTWvM (ORCPT ); Thu, 20 Aug 2020 18:51:12 -0400 Received: from mail-ed1-x541.google.com (mail-ed1-x541.google.com [IPv6:2a00:1450:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4355C061385 for ; Thu, 20 Aug 2020 15:51:11 -0700 (PDT) Received: by mail-ed1-x541.google.com with SMTP id i26so2948115edv.4 for ; Thu, 20 Aug 2020 15:51:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ePlmLgzCtlWiuxoxVh29CyOsClISbIT4agaEsQKgw3M=; b=uUq1JRoVwV5dgmD1bEihR7hgqEJ37LwyXI62GhBQPPv0GhdesNRF0WZD+CdVrsIFnz QenIAW7xB7I0Y2C1yX+hi4veAg2gp5dRfXjDATES9etO2s61gHxkiu2/Uuh3+eMcCgc/ a0mFSoouAPESgYaK2pqCo49pzjTSNDIh0tq/vUum0RljEoinVbLcPxiRYXMqy//qcFY7 0iEPz4Z9IOuOE5IipecBEgKd3FdIxrWUGuhhDikbpfd08frdNdgbsGWVpGB0E09Ac3a/ tre4r8etg5mDkFpzLsCZ7ZmSIrSov3qHivGX6LnjaHrech5YOF4qr7qBgQ2PH5ri+C+s LKbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ePlmLgzCtlWiuxoxVh29CyOsClISbIT4agaEsQKgw3M=; b=ggEVQJCx4OZDVkwLlpTeo0J8uRdx3gxDmSGfqBK9HNqAlomcA7yrPXyccKfs35wDI0 IE9bmKlsbPqPiR5dfLBMnsxnwsBZdoTQtZlKNgbklHs6bsO53x3qXI6kBQWMhseAuJqc qYIwm15neCw4SIzWKEGnogauq0a9MTN6z4q5M+QgQqEupNC++pAkYYIwoR93SXjyGcMo BbRdxUW+W6JKPucLAZgRxPhMYJTE/n3Y8jjkwvEWyDF33WCEtc0trl9+n4Ss8+0K34DB usbV3D9J/qaG9+1QuVh8X/8jlD7GyvT4pePTVtiPhDNSOrfgmrJ9A7lbr8TaqSEmh1jr 4wsA== X-Gm-Message-State: AOAM530b4/fkwubDkj27TJyh8RoRsZWDCwO8jz1r1f44AF57gg46rqmO z9VhYuyPsiXSIpBEhO6DYeRIlL1kwqa0bFuNIdE= X-Google-Smtp-Source: ABdhPJwM7phxMUBEe035p/BY+gY+gx8VvnycFblnAm+mDThc4JLA6vCyiQGG6wWu0Y01pzoMW1bfEYhNp0K4OW9Z5DY= X-Received: by 2002:a50:fd8d:: with SMTP id o13mr15089edt.313.1597963870368; Thu, 20 Aug 2020 15:51:10 -0700 (PDT) MIME-Version: 1.0 References: <20200818184122.29C415DF@viggo.jf.intel.com> <20200818184136.7FD537AA@viggo.jf.intel.com> In-Reply-To: <20200818184136.7FD537AA@viggo.jf.intel.com> From: Yang Shi Date: Thu, 20 Aug 2020 15:50:57 -0700 Message-ID: Subject: Re: [RFC][PATCH 8/9] mm/vmscan: never demote for memcg reclaim To: Dave Hansen Cc: Linux Kernel Mailing List , Yang Shi , David Rientjes , Huang Ying , Dan Williams Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 18, 2020 at 11:52 AM Dave Hansen wrote: > > > From: Dave Hansen > > Global reclaim aims to reduce the amount of memory used on > a given node or set of nodes. Migrating pages to another > node serves this purpose. > > memcg reclaim is different. Its goal is to reduce the > total memory consumption of the entire memcg, across all > nodes. Migration does not assist memcg reclaim because > it just moves page contents between nodes rather than > actually reducing memory consumption. > > Signed-off-by: Dave Hansen > Suggested-by: Yang Shi > Cc: David Rientjes > Cc: Huang Ying > Cc: Dan Williams > --- > > b/mm/vmscan.c | 33 +++++++++++++++++++++++++-------- > 1 file changed, 25 insertions(+), 8 deletions(-) > > diff -puN mm/vmscan.c~never-demote-for-memcg-reclaim mm/vmscan.c > --- a/mm/vmscan.c~never-demote-for-memcg-reclaim 2020-08-18 11:36:56.442583170 -0700 > +++ b/mm/vmscan.c 2020-08-18 11:36:56.447583170 -0700 > @@ -296,8 +296,11 @@ static bool writeback_throttling_sane(st > #endif > > static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, > - int node_id) > + int node_id, > + struct scan_control *sc) > { > + bool in_cgroup_reclaim = false; > + > /* Always age anon pages when we have swap */ > if (memcg == NULL) { > if (get_nr_swap_pages() > 0) > @@ -307,8 +310,18 @@ static inline bool can_reclaim_anon_page > return true; > } > > - /* Also age anon pages if we can auto-migrate them */ > - if (next_demotion_node(node_id) >= 0) > + /* Can only be in memcg reclaim in paths with valid 'sc': */ This comment looks not right. The global reclaim also has valid 'sc' but just with NULL target_mem_cgroup. > + if (sc && cgroup_reclaim(sc)) > + in_cgroup_reclaim = true; > + > + /* > + * Also age anon pages if we can auto-migrate them. > + * > + * Migrating a page does not reduce comsumption of a s/comsuption/consumption > + * memcg so should not be performed when in memcg > + * reclaim. > + */ > + if (!in_cgroup_reclaim && (next_demotion_node(node_id) >= 0)) > return true; > > /* No way to reclaim anon pages */ > @@ -326,7 +339,7 @@ unsigned long zone_reclaimable_pages(str > > nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) + > zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE); > - if (can_reclaim_anon_pages(NULL, zone_to_nid(zone))) > + if (can_reclaim_anon_pages(NULL, zone_to_nid(zone), NULL)) > nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) + > zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON); > > @@ -1070,6 +1083,10 @@ bool migrate_demote_page_ok(struct page > VM_BUG_ON_PAGE(PageHuge(page), page); > VM_BUG_ON_PAGE(PageLRU(page), page); > > + /* It is pointless to do demotion in memcg reclaim */ > + if (cgroup_reclaim(sc)) > + return false; > + > if (next_nid == NUMA_NO_NODE) > return false; > if (PageTransHuge(page) && !thp_migration_supported()) > @@ -2369,7 +2386,7 @@ static void get_scan_count(struct lruvec > enum lru_list lru; > > /* If we have no swap space, do not bother scanning anon pages. */ > - if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id)) { > + if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id, sc)) { > scan_balance = SCAN_FILE; > goto out; > } > @@ -2653,7 +2670,7 @@ static void shrink_lruvec(struct lruvec > * rebalance the anon lru active/inactive ratio. > */ > if (can_reclaim_anon_pages(lruvec_memcg(lruvec), > - lruvec_pgdat(lruvec)->node_id) && > + lruvec_pgdat(lruvec)->node_id, sc) && > inactive_is_low(lruvec, LRU_INACTIVE_ANON)) > shrink_active_list(SWAP_CLUSTER_MAX, lruvec, > sc, LRU_ACTIVE_ANON); > @@ -2724,7 +2741,7 @@ static inline bool should_continue_recla > */ > pages_for_compaction = compact_gap(sc->order); > inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); > - if (can_reclaim_anon_pages(NULL, pgdat->node_id)) > + if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc)) > inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); > > return inactive_lru_pages > pages_for_compaction; > @@ -3485,7 +3502,7 @@ static void age_active_anon(struct pglis > struct mem_cgroup *memcg; > struct lruvec *lruvec; > > - if (!can_reclaim_anon_pages(NULL, pgdat->node_id)) > + if (!can_reclaim_anon_pages(NULL, pgdat->node_id, sc)) > return; > > lruvec = mem_cgroup_lruvec(NULL, pgdat); > _